Method for processing billets out of metals and alloys and the article

ABSTRACT

This method refers to a method by which the physical and mechanical properties intrinsic to a fine-grain structure may be formed in metal billets using pressure treatment. The method is designed to treat rods, bars and other particularly long billets. This method is designed to lower the cost of deformational treatment for long rods and large diameter billets and creates a pre-specified microstructure, including micro-crystal structure, and specific physical and mechanical properties. This may be achieved using various treatment techniques, one of which includes the deformation of at least a part of the billet through reduction of the billets cross-section. In this method, a long rod shaped billet is used. Reduction of the cross-section is achieved using tools that permit movement along and across the billet&#39;s axis as well as being rolled about its surface, for example, a roller. In this case at least one support stand is employed for correct placement of the billet. Additionally, a pre-specified strain level is achieved using at least one of the techniques of deformation: torsion, settling and extension using tools, for example the above-mentioned stand. The stand is designed to apply a specified scheme of deformation to the billet at the deformed (strained) section and at a specified temperature. This obtains specified structure with intrinsic physical and mechanical properties.

BACKGROUND OF THE INVENTION

This method relates to a method of pressure treatment for metal billetsthat have specified physical and mechanical properties, which arederived from their fine grain structural characteristics. The methodrelates to treating rods, bars and other particularly long billets.

It is known that physical and mechanical properties, for examplestrength and plasticity, depend on a material's microstructure.Therefore, changes to the microstructure characteristics may changethese properties. For example, it is usually necessary to create acellular or sub-grain microstructure within the material to strengthen amaterial.

Large physical and mechanical changes of a material's properties may beachieved by refining the micro-crystal grains, for example those grainsthat are sized from 10 to 0.1 μm. These materials, when compared withcoarse grain materials, exhibit significantly higher strengthcharacteristics. At higher temperatures these materials exhibit low flowpressure and higher levels of plasticity, or even super-plasticity. Inorder to form a micro-crystal structure, it may be necessary to use moreradical deformation techniques than those used to create other types offragmented microstructures, for example sub-grain microstructures.

Known billet deformational treatment methods comprise equal-channelangular extrusion and pressure torsion. These methods are used toproduce billets with specified physical and chemical characteristics,because the methods produce known micro-crystal structures. Thesemethods also permit the development of small mass and sized fine-grainbillets. These methods are, however, highly labor and energy intensive.

Another metal and alloy deformational treatment method comprisesdeformation that is done by multiple reduction steps and is generallyfollowed by an increase in cross-section by extrusion and upsetting.This method permits development of small sized rods from soft materials,in which the rods have smaller physical and chemical properties.

Billet treatment involves significant energy consumption because of theforce required to overcome friction that is generated when the surfaceof the machine tool and billet meet to overcome hydrostatic pressurecreated during extrusion, for example extrusion using backwater. Thismethod is generally unsuitable for the production of large-sizedbillets, for example billets in the form of rods that are five to sixmeters in length with a 150-200 mm minimal diameter formed from a hardto deform alloy. In this situation, it is necessary to use an apparatusincluding a press that can develop up to several tens of thousands ofton pressure as well suitable machine tools. Typically rods with amicro-crystal structure or grains sized from 3 to 8 μm and a diameter of30 to 40 mm are produced by multi-operational forging or rolling methodsfrom billets with an initial diameter of 400 mm or larger.

SUMMARY OF THE INVENTION

The method reduces the cost of deformational treatment for long rods andlarge diameter billets that require a specified internal microstructure,including micro-crystal microstructure, and specified physical andmechanical properties. This specified internal microstructure may beachieved using various treatment methods, including deformation of abillet section through reduction of a billet's cross-section. Reductionof the cross-section uses tools, for example a roller, that permitmovement along and across the billet's axis and as well being spinningthe billet about its surface. At least one support stand can be used forcorrect positioning and placement of the billet. Additionally, apre-specified strain level can be achieved using a deformation thatincludes one of torsion, upsetting, and drawing, that uses machines suchas the above-discussed stand. The stand applies a specified deformationto the billet at the deformed, or strained, section at a pre-specifiedtemperature. This deformation obtains a specified microstructure withintrinsic physical and mechanical characteristics.

It is recommended that reduction of the billet's cross-section, using ahot-metal roller, be done by applying pressure along the billet's axisusing stands and clamps; reducing the billet's cross-section bylaterally moving the billet through rollers; reducing the billet'scross-section by longitudinal and lateral moving the billet throughrollers; reducing the cross-section by moving the billet through rollersthat the rotational axes create crossed angles with the billet's axis;reducing the billet by passing the billet through rollers located at120° from each other, and choosing a length of the treated section notto exceed three minimal diameters of the rod's reduced cross-section.Further, the reduction of the billet's cross-section, which uses ahot-metal roller, may be done while applying torsion using stands androllers; applying reverse torsion; and applying deformation of thebillet's cross-section using a figure roller. The roller profileincludes several sections, including a middle section that includes thelargest cross section; an intermediate section on both sides of themiddle section that have the smallest cross-section; and two endsections.

Alternatively, the method for billet reduction using a hot-metal roller,is by reducing a cross-section through compression along the billet'slongitudinal axis; or allowing upsetting the billet after passing thebillet through rollers about its lateral axis, in which the length ofmovement is not greater than the amount of lateral deformation for thissection during reduction); allowing the billet's upsetting afterlongitudinal and lateral rolling about the billet's axis; upsetting thebillet while rolling under the following condition:

σ_(u)>σ_(i)<σ_(e),

where σ_(i) is the level of stress on the strained section, determinedby considering the deformation resistance produced by the rollers duringrolling, and σ_(u) is the stress caused by loss of the billet'sstability, and σ_(e) is the stress caused by compression of the billet'sundeformed sections.

Furthermore, the reduction of the billet's cross-section comprisesrolling using a hot-metal roller while continuously and consecutivelydeforming the length of the billet under treatment; and treatingsections of the billet in which the distances between each section arenot greater than 3 times the diameter of the billet after treatment.

For a billet formed of single-phase alloys, the deformation methodincludes deformation is done with a real strain amount is not less than3, and in particular with a strain amount of 1.4, with the strain rateof 10¹-10⁻² s⁻¹ at a temperature of (0.3-0.5) T_(melt)), where T_(melt)is melting point. For billets formed of a multi-phase alloy, deformationis done with a real strain amount of not less than 3, in particular witha strain amount of 1.4, and with a strain rate of 10⁻¹-10⁻⁴ s⁻¹ at atemperature of(0.5-0.85)T_(melt), where T_(melt) is melting point.

For titanium alloy billets that comprise a lamellar structure, thedeformation method, with a real strain amount of not less than 3,comprises reduction or applying torsion with rolling and upsetting thatoccurs simultaneous the rolling. These steps are done in addition to thereducing, upsetting, and deforming at 700—Ta.t. and a strain rate10⁻¹-10⁻⁴ s⁻¹, where Ta.t. an allotropic transformation temperature. Forsections of titanium billet with a lamellar structure, the method isdone with not less than 1.1 times reduction of the billet cross-sectionat temperature of Ta.p−Ta.p.+(10-50), followed by a coil step at a rateof not less than 1°/s, and applying torsion and upsetting at atemperature not higher than 700-Ta.p. and strain rate of 10⁻¹-10⁻⁴ s⁻¹.

For heat resistant nickel billets, the method includes deforming attemperatures not higher than the temperature of complete dissolution ofthe γ′—phase, deforming each billet section within 10%-20% of thespecified temperature and strain amount, so as not to a change in thestress flow σ_(f) more than 5%/-10%; and deforming each billet sectionat a specified temperature and strain amount ξ until changes of thestrain amount do not increase of the coefficient of the sensitivity ratem=(log N₁-log N₂)/(log ξ₁-log ξ₂) up to amounts of 0.3-0.8; in which N,and N₂ are pressure amounts (moment, pressure of compression, orextension at the corresponding deformation) that are applied to thebillet, both before and after the change of the strain amount from theamount ξ₁ to the amount ξ₂

FIG. 1 illustrates a unit's components for the method, as embodied bythe invention;

FIG. 2 illustrates cross section A-A of the unit of FIG. 1;

FIGS. 3A-3H illustrate schemes of the treatment method, as embodied bythe invention, at different stages in the method;

FIG. 4 illustrates a unit, as embodied by the invention;

FIG. 5 illustrates a microstructure of a BT8 titanium alloy samplebefore treatment; and

FIG. 6 illustrates a microstructure of the BT8 titanium alloy sample(FIG. 5) after treatment using the method, as embodied by the invention.

In the method, as embodied by the invention, a treated section issubjected to “geometric” de-hardening through cross-section reductionusing rollers. The method of the invention deforms of a billet,including sections of the billet's central part. The method also createsconditions for further material treatment. The deformation is notdistributed or scattered over the entire billet. Instead, thedeformation is localized Within selected reduction zones of the billet.Therefore, structural changes to the billet are done only in theparticular billet section. A number of different deformation techniquesand steps are employed in the method, including rolling, extension,compression, and shearing (torsion). Additionally, the amount andpredominant direction of deformation facilitates the formation of thestructural changes in the billet.

The temperature that is used in forming a specified microstructure withcertain mechanical properties lends to the localization of thedeformation. This temperature dependence is due to thermal de-hardeningof material. The temperature that is applied to a billet section, aswell as any varying of the temperature, can influence the formation ofdifferent specified microstructure, for example micro-crystal structurethat develops as a result of the initial and dynamic re-crystallizationof deformed material. The formation of a given micro-crystal structuremay occur over a wide temperature range. The selection of a temperaturerange for heat treatment of a billet section or the entire billet,depends on the billet material or the microstructure that the method isdesired. For example, in the production of a fine-grain microstructurein metals and single-phase alloys, deformation is done at lowertemperatures compared with multi-alloyed and multi-phased metallicmaterials.

Deformation, as embodied by the invention, typically comprises rollingreduction of billet, and includes one of: applying torsion, upsetting,or drawing processes. The deformation process, and the extent to whichthe process is used, depends on at least one of: intensity ofdeformation, the microstructure desired, the billet's initialcomposition, the initial size and shape of the billet, and the finalsize and shape of the billet.

Usually only one deformation process is applied to a billet that has arelatively small cross-section. For example, torsion can be applied to asmall cross-section billet to reduce its grain size on a surface layer,as compared to a middle section. Torsion may also be used whenalteration of a billet's cross-section is not required. To create a moreunified microstructure within a billet cross-section, drawing andupsetting processes may be used. The upsetting process generallyproduces a rod with a cross-section that is close to or larger than therod's initial cross-section. The extension associated with upsetting canproduce a smaller billet cross-section than that which the billetinitially possessed.

Torsion can be applied to create a uniform microstructure within a givenbillet cross-section without drawing or upsetting, if the application oftorsion is done at temperatures close to those at which super plasticdeformation (SPD) occurs. Accordingly, a reduction of a given grain sizeoccurs. During the application of torsion, changes occur within innerregions of the billet, and generally insubstantial changes occur atexternal layers due to known characteristics of SPD. These steps resultin the formation of a uniform fine-grained microstructure in a billet.

Several deformation techniques (steps) may be used for treating of a rodwith a relatively wide cross-section. These techniques can be employedconsecutively or simultaneously. Multiple deformation techniques usedsimultaneously decrease axis pressure during deformation. Additionally,treatment of the same section can be repeated by reapplying the previouscombination of deformation techniques or by using a modified combinationof techniques. For example, decreasing a heating temperature during asubsequent heat treatment session can result in a finer fine-grainmicrostructure than that which would resulted from just one heattreatment. The overall result of a combination of different treatmentsproduces varying deformation characteristics. Therefore, treatments thatare sufficient for the formation of desired and specified physical andmechanical properties of the billet are done.

The particular techniques, and the extent, to which they are used toachieve a particular microstructure, can be influenced by thedeformation characteristics of the material. For materials prone tolocalized deformation, for example titanium alloys, it may be necessaryto simultaneously treat the billet using several techniques Thistreatment increases the homogeneity of deformation. A similar treatmentis useful for alloys of low plasticity, such as heat resistant nickelalloys. For heat-resistant nickel, an increased deformation homogeneityleads to an increase in the deformation of the billet. Further, formaterials with a large variety of possible creep systems, for examplesingle-phase nickel alloys, treatment with at least one of theabove-described technique is possible.

An economic efficiency, as embodied by the invention, is determined withreference to the amount of energy and materials consumed. To transform acoarse grain microstructure into a fine grain microstructure, extensivedeformation of relatively small billet sections may be required.Extensive billet deformation can be done using multiple and repetitivetechniques, such as extruding and upsetting of the billet. However,these techniques are highly energy intensive. Another energy intensivemethod is comprehensive billet forging, which is often used to produce ahomogeneous fine grain microstructure. Multiple heating of the billetmay be required since a single heat treatment will not achieve a uniformgrain size reduction in these materials. Multiple heating is highlyenergy intensive, and is a multi-forging technique requiring upsettingof the billet with alternating compression directions. This techniqueresults in billet sections with intense deformation, minor deformationand sections where deformation is not present. This type of deformationdistribution leads to excessive energy use because strain recoveryoccurs in the under-treated sections. Therefore, in these sections, moreenergy is used to accumulate structural defects that are needed forre-crystallization method.

In the method, as embodied by the invention, deformation is localized inthe billet. Therefore, a re-crystallization dislocation density can bereached in the localized much faster when compared with upsetting andforging. Additionally, the energy consumption to overcome frictionforces is decreased. This decrease is because creep friction that occursduring extruding and upsetting is replaced by rolling friction byrollers.

The raw material savings that result using the method, as embodied bythe invention, as opposed to forging, result from a reduction in thenumber of production steps to achieve a particular microstructure. Themethod can comprise a one step method; so loses of metal due to repeatedheating and flash removal are avoided. The method, as embodied by theinvention, also permits the production of billets that are free fromminor reductions of cross-sectional diameters. Rods of a small initialdiameter may be treated by the method, as embodied by the invention,rather than forging. Therefore, it is possible to avoid the use of largediameter billets that lack chemical, phase and grain homogeneity.

The method, as embodied by the invention, does not need heavy equipmentand heavy load presses. Forces for achieve upsetting are less than thatinvolved during the known upsetting. Additionally, the method, asembodied by the invention, can be used to correct a rod shape, such asits curvature and circumference. This method also promotes materialsavings, and the rolling improves shaping accuracy and surface clarity(also known as its “finish”).

The method, as embodied by the invention, permits the production oflarge diameter long rods that possess physical and mechanical propertiesthat correspond to a fine-grain structured material. The method allowsproduction of a shaft, in which a part includes increased heatresistance as a result of a relatively coarse grain structure and otherparts include high strength characteristics from grain refinement. Themethod, as embodied by the invention, also permits the manufacture ofbillets with various sized cross-sections, diameters, and lengths, andcan maintain an initial billet size.

The following examples of methods, as embodied by the invention, providea billet with material plasticity: rolling and applying an extensionforce along a billet's axis during reduction to elimination of ridgeformation from the material displaced by rollers; rolling the billetthrough at least three rollers, which can be located at 120° from eachother, created by side hydrostatic backwater, applying reverse torsion,as the changes in deformation direction and increase in creep areevident; and reducing by applying compression along a billet's axis.Additionally, upsetting steps can be done simultaneously with rolling.

For increasing billet stability during treatment, the followingtechniques (steps) can be employed: upsetting a billet after rollingabout its lateral axis, in which the movement amount should not begreater than the lateral deformation amount; and upsettingsimultaneously with rolling under the following conditions:σ_(u)>σ_(i)<σ_(e).

Additional methods, as embodied by the invention, include: upsettingafter longitudinal and lateral rolling about the billet's axis;continuously and consecutively deforming the length of the billet undertreatment pressure; and rolling the billet so that the rotational axescreate crossed angles with the billet's axis rollers that are located at120° from each other.

Deforming a billet section that has a length not greater than threebillet's diameters can produce structurally inhomogeneous billetsections. The billet ends will possess a fine-grain microstructure,while middle parts possess a coarse grain microstructure. Afterupsetting, the billet may be formed into homogeneous discs.

The methods, as embodied by the invention, include heating to aspecified temperature and subjecting to strain ε_(tr) at a strain rateto produce a fine-grain microstructure. To produce a material withsmall-angled grains (sub-grains), a strain amount of ε_(tr)=0.3-0.6 isappropriate, when ε_(tr) is a true strain. When refining grains up to 10μm, the strain amount should be ε_(tr)≧3, while to formsub-micro-crystal or nano-structure, the true strain amount is ε_(tr)≧5.Accordingly, a higher strain corresponds to a smaller sized grain.

For single-phase materials, lower heating temperatures can be usedbecause of grain growth characteristic differences compared withmulti-phases materials A microstructure of multi-phases materials ismore stable so a dissolution temperature, which suppresses the growth ofgrains, limits the upper temperature limit. The lower temperature limitis determined by a material's diffusion activity. For example, for heatresistant nickel alloys, the heating temperatures are 0.5 T_(melt),where T_(melt) is the melting point as well as the dissolutiontemperature for the hardening intermetallic phase. For titanium alloybillets, the heating temperature is limited to (T_(a.t.) −150° C.),where T_(a.t.) is the temperature of the allotropic transformation.

A strain rate, as embodied by the invention, corresponds to thesuper-plasticity condition because transformations are intensified. Fortitanium alloys to achieve a complete transformation to a fine-grainedmicrostructure, several deformation techniques can be usedsimultaneously. These techniques may include applying torsion, rolling,and upsetting. Another method, as embodied by the invention, to treatlarge cross-section titanium alloy rods heats a billet to a temperatureof T_(a.t.)−T_(a.t.)+(10-50)° C., followed by reducing its cross-sectionfrom 1.5-2 times. The treated section is then cooled or quenched at arate of not less than 1° C./s. Torsion and upsetting may then beapplied, for example by rollers, at a temperature not higher thanT_(a.t.) This method increases hardnenability and causes development ofthin colonies of α-phase grains. Additionally, this method promotes thedevelopment of a more homogeneously dispersed microstructure duringdeformation treatment at temperatures below the allotropictransformation temperature.

The method, as embodied by the invention, allows monitoring of themechanical parameters of deformation, such as the coefficient of therate sensibility of the stress flow m. This coefficient is monitoredduring tension, extension, and compression treatments. Precisemonitoring at stages during torsion treatment is possible to assess thetransformation of the initial structure into the required micro-crystalmicrostructure. If m is greater than 0.3, or with further increases ofdeformation pressure amounts does not change significantly, then majorstructural changes are complete and that a fine-grained microstructurehas been formed.

EXAMPLES OF THE METHOD IN OPERATION

FIGS. 1 and 2 illustrate the unit that applies the steps of the method,as embodied by the invention. The unit comprises a frame 1, furnace 2,and three rollers 3, 4, and 5. The rollers are inserted into the furnacethough windows 6, 7, and 8. The unit also contains hydro-cylinders 9,10, and 11 for lateral transformation of the rollers. A carriage 12 ismounted on a frame or plate 13 may be moved incrementally along guides14, 15 within the frame 13. Bearings 16 and 17, gears 18 and 19, and adrive 20 rotate of frame 1. Mobile stands 21 and 22 are located within abody of pins 23 and 24. The pins correspondingly are mounted on thebearings 25, 26, 27, and 28 in the bodies of left 29 and right 30stocks. The stocks 29 and 30 are also mounted on the frame 13 formovement along the guides 14 and 15. The end parts 31 and 32 of the pins23 and 24 act as clamps during torsion and extension of the billet. Amechanism for griping billets between clamps is not illustrated in FIG.1. Additionally, the unit has drives 34 and 35 for moving the stands 21and 22 and loading the billet 33 with axial forces. The drives 36 and 37are use to move the pins 23 and 24 with clamps 30 and 31. Electricmotors 38 and 39 provide torsion forces to the billet 33 throughredactors 40 and 41, and bearings 42, 43, 44, and 45 and pairs of gears46 and 47, and 48 and 49.

FIGS. 3A-3H illustrate systems for treating the billet, as embodied bythe invention. The figures illustrate that stands 21 and 22 can be movedalong the billet's axis, and also permit reverse torsion applicationsusing clamps 31 and 32 and three rollers 3, 4, and 5 located at an angleof 120°. Roller 5 is not illustrated in FIG. 5.

FIG. 4 illustrates operation of the unit. The stands 51 and 52 can bemoved along the sample's axis and permit application of reverse torsionusing clamps 53 and 54. Furnace 55 provides a heat source 56 with whichto heat the billet. At the billet's butt-end 50, slots 57 and 58 areintroduced to aid movement during torsion. Inserts 59 and 60 thatimitate the role of the rollers and stabilize the billet duringupsetting hold the treated section 56. A clamp 61 stabilizes the insertsduring the upsetting and application of torsion steps. The clamp andinserts are made from the softer material than the billet undertreatment.

Example 1

A method, as embodied by the invention, is done in a unit as illustratedin FIG. 1. The explanation of the method is with respect to FIGS. 3A-3H.The rod-shaped billet 33 is several times longer than it is wide. Whentreatment commences, the billet is mounted on stands 21 and 22 and heldbetween clamps 23 and 24. The rollers 3, 4, 5, along with the furnace 2,move the section on a carriage 12 along the frame 13. The func 2 is notillustrated in the figures.

Generally, the particular section selection for treatment isunrestricted. However, selection of a given section depends on thepurpose for which it will later be used. If the middle of a billet 33 isto be treated, then the ends of the billet are located on stands 21, 22and held with clamps 23, 24. Thus, rollers 3, 4, 5 along with thefurnace 2 move the treated part on a carriage 12. If treatment of thewhole billet 33 is desired, the furnace 2 and rollers 3, 4, 5 are movedfrom one end of the billet, for example, the right one. In thisscenario, the rollers act as stands.

After heating the billet 33 to the deformation temperature, the billetis rotated by electric motors 38, 39, redactors 40, 41, and pairs ofgears 46-49. Reduction is done by rolling of sections of billet, andalso as a result of roller transportation in the lateral axis of thebillet. This movement may be achieved using hydro-cylinders 9, 10, 11.To improve the reduction of the billet's ends and preventing formationof ridges (buckling) on the unreduced section surface, the rotationalaxis creates specific crossed angles within the billet's axis. In thiscase, force is directed along the billet's axis. This force providesdisplacement of part of the treated section in the direction of thebillet's axis. The amount of this displacement is equal to the amountdisplaced by rollers. FIG. 3C illustrates sectional reduction of thepart that is not located at the billet end. Extension forces F areapplied though clamps 31, 32. As in the previous case, ridges are notcreated because the impact of the rollers and clamps providedisplacement at either end of the billet. As before, the amount of thisdisplacement is equal to the amount of the metal that is displaced byrollers. In FIG. 3C this displacement is illustrated by the dottedlines. The length of the reduced section is limited by the billet partthat is heated up to the deformation temperature. FIG. 3D illustratesthat the length of the reduced section is greater then the length of therollers. Moments M, which have opposed directional forces, are appliedto the ends of the billet. These moments M provide plastic torsion ofthe treated section (FIG. 3E). During plastic torsion, the surface isrolled, and after torsion, depending on the cross-sectional size of rod,the rollers and furnace are moved along the billet's axis or upsettingis applied. Then treatment of the next section begins.

Movement to a new billet section can be done by a step-by-step bylateral roller removal from the billet, placing the rollers along thebillet's axis and repeating the steps on the next billet section byplacing the rollers along the billet's axis. The rollers rotational axescreate angles with the billet's axis, simultaneously moving the rollersalong and across the billet while applying extension forces.

Upsetting is done by application of compression forces P on the billet.Rolling of the billet section under treatment is simultaneous withupsetting to provide deformation homogeneity. Upsetting can usedifferent steps. One step is illustrated in FIGS. 3D and 3E. Before theupsetting begins, the rollers are moved to one end of the billet, forexample the right end. Accordingly, a gap δ is formed between therollers and the left side of the billet. The positioning of the rightside rollers and stand is fixed. The left stand is then displaced byamount Δ. This amount is sufficient to conduct, through the applicationof force P, upsetting on the left-hand side of the treated section. Theupsetting continues until the gap disappears.

Also, upsetting is done along the entire length of a treated billetsection. The stands, together with the movement force, apply pressureforces P to the billet. Additionally, the rollers move laterally andincrease of the diameter of the strained section to roll the billetsurface and prevent the barrel formation. To decrease the strainpressure and increase the homogeneity deformation, the billet section issimultaneously treated applying plastic torsion and upsetting. Upsettingcan be applied simultaneously with the above-described rolling. Thismethod continues until all sections between the stands are treated, asin FIGS. 3F and 3G. A butt-end of the billet is treated using the samesteps as those applied at the beginning of the billet. Upsetting stepsfor a billet are shown in FIG. 3H.

Example 2

Several alloys are treated using the method, as embodied by theinvention. The treatments are done using two-phase titanium alloy “BT8”possessing an initial, coarse lamellar structure. The titanium (α+β)alloys tend to exhibit localizes deformation, however lamella α—phasesare stable. Thus, these alloys do not form a homogeneous micro-crystalstructure as readily as heat resistant nickel alloys. In addition to BT8alloy, a multi-phase heat resistant nickel alloy “ÝÏ962” is treated. Inorder to reduce costs, the treatments were done on alloys with adiameter of 15 mm and length of 50 mm using the unit illustrated in FIG.4.

Example 2.1

The treatment investigated producing a specified microstructure,including a homogeneous globular micro-crystal microstructure in onesection of two-phase titanium alloy BT8 sample. Several samples areproduced. Initially, the samples possess a lamellar microstructure (FIG.5). The size of the transformed β-phase grains are 1500-2000 μm, andcolonies of α-phase grains are 200-300 μm. The section to be treated hasa diameter and length of 10 mm. During compression, the cross-sectionalsize of the section is close to its initial diameter. Samples 1, 2 and 3are treated using the method, as embodied by the invention, at 950° C.;sample 4 is treated according to the conditions in Table 1. This Tablealso contains the results of the treatments.

TABLE 1 Sample Number Treatment Conditions Treatment Results 1 Upsettingto reduce a section Bent and crashed plates into with the true strainequals 1. fragments with partial structural globalization. 2 Torsion ofreduced section on 85% formation of a globular two turns with thefollowing structure with an average upsetting with true strain grainsize of 5 μm. equals to 1. Average summed strain of the billet is 3. 3Torsion of the reduced section 95% formation of a globular on 8 turnsand upsetting with structure with an average the true strain equal to 1.grain size of 5 μm. Average summed strain of the billet equals 8.5. 4Torsion of the reduced section Formation of a on 8 turns and upsettingwith homogeneous globular the true strain equals 1. structure throughoutthe Average summed strain of the cross-section. billet is 8.5.

Example 2.2

This treatment is designed to create a micro-crystal structure in heatresistant nickel alloy using the method and steps, as embodied by theinvention A sample of a coarse-grain heat resistant nickel alloy(ÝÏ962), with an average grain size of 100 g,m is held in clamps asillustrated in FIGS. 3A-3H. The sample was heated to a temperature of1080° C. After heating, plastic torsion is applied to the billet.

The application of torsion is done until the sample is no longerstable-up to 5% from an average amount. The upsetting is done until thediameter of the section is approximately equal to its initial diameter.Torsion is applied simultaneously with an application of strain. Anaverage summed strain amount is 3.8. Metallographic analysis revealsthat a micro-duplex microstructure forms with matrix grain sizes with a3-4 μm range and inter-metallic phase grain sizes with a 1-2 μ range.The method, as embodied by the invention, produces grain refinement indifferent materials. Additionally, the method confirms that astructurally inhomogeneous billet could be produced.

Example 2.3

A sample of a titanium alloy (BT8) with a lamellar structure wastreated. This treatment produces an inhomogeneous structure with adiameter of 15 mm and length of 20 mm. The butt-end microstructure (adistance from the ends at about 5 mm) should be a micro-crystalmicrostructure with the middle section being of coarse grain with alamellar microstructure. Two 10mm sections located 20 mm from each otherare treated as in Example 2.1. The middle sections are then cut. Thesample is then subjected to upsetting. The strain amount is 80% with astrain rate of 10⁻³ s⁻¹ at 950° C. For comparison purposes, ahomogeneous coarse-grained billet is subjected to upsetting under thesame conditions. Results indicate that in a structurally inhomogeneoussample, the “barrel shape” and under-formed zones are absent while aglobular homogeneous microstructure is formed. However, thecoarse-grained homogeneous sample exhibited “barrel shape” sides, endzones without deformation and a globular microstructure. This Exampledemonstrates advantages of the method, as embodied by the invention.

Theoretical Results and an Assessment of the Method When Applied toOver-Length Billets

Treatments using full-length large diameter billets are expensive, thusa theoretical assessment of different conditions and steps, as embodiedby the invention, were done. The deformation amount of applied forceneeded treatment time, and initial pressure amount necessary to commenceupsetting without encountering loss of the billet's structural stabilitywere assessed. The results indicate that the method, as embodied by theinvention, can comprise several deformation steps appliedsimultaneously. For example, applying reduction, drawing, upsetting, andapplying torsion simultaneously can produce refined grains. The steps ofholding deformation for grain refinement as well as decreasing axialpressure provided desirable results. For example, during the applicationof torsion, the pressure for upsetting a given billet section with adiameter in a range from 100 to 250 mm, is less than 10 tons at a strainrate of 5 mm/min and 60 tons at the strain rate of 50 mm/min. Forupsetting without torsion, applied pressure of 3 to 5 times the abovemay be needed. In comparison, micro-crystal structured rods with a100-250 mm diameter formed from heat resistant nickel and titaniumalloys can be produced by extrusion (pressing) and applying severalthousand tons of force. Calculations show that upsetting with torsionpressure deforms a billet without causing a loss of structuralstability. Therefore, forces applied are less than a critical force thatcauses the billet to bend. Accordingly, the torsion moment required fora billet, with a diameter of 100 to 300 mm, is 1-14 tm.

The time to create a fine grain microstructure in a 100 mm long section,at the above-mentioned strain rate, is 2-10 minutes, and for a 2 meterrod length, with the diameter of 100-300 mm, is about 2 hours. Thesetimes are comparable with times for isothermic forging of billets withdiameters of 200 mm and lengths of 400-500 mm.

While various embodiments are described herein, it will be appreciatedfrom the specification that various combinations of elements, variationsor improvements therein may be made by those skilled in the art, and arewithin the scope of the invention.

We claim:
 1. A metal and alloy treatment method, the method includingdeformation of at least a section of a billet through reduction of thebillet's cross-section, the method comprising: providing a long billet;providing at least one support stand for positioning the billet alongits longitudinal axis and rolling the billet around its longitudinalaxis; reducing the billet's cross-section by applying a pressure alongand across the billet longitudinal axis; and deforming the billet byapplying torsion and extension forces; wherein a microstructure isprovided with intrinsic physical and mechanical characteristics.
 2. Amethod according to claim 1, wherein the step of reducing a billet'scross-section comprises applying pressure along the billet's axis usingstands and clamps.
 3. A method according to claim 1, wherein the step ofreducing a billet's cross-section comprises laterally rolling the billetwith rollers.
 4. A method according to claim 1, wherein the step ofreducing a billet's cross-section comprises longitudinal and lateralrolling the billet through rollers.
 5. A method according to claim 1,wherein the step of reducing a billet's cross-section comprises rollingthe billet and creating forces directed at angles to the billet throughrollers in which the rotational axes create crossed angles with thebillet's axis.
 6. A method according to claim 1, wherein the step ofreducing a billet's cross-section comprises passing the billet throughthree rollers located at 120° from each other.
 7. A method according toclaim 1, wherein the length of the deformed billet does not exceed threeminimal diameters of the billet's reduced cross-section.
 8. A methodaccording to claim 1, wherein the step of reducing of the billetcomprises applying compression along the billet's longitudinal axis. 9.A method according to claim 1, wherein the step of deforming comprisesapplying torsion comprises using stands and rollers.
 10. A methodaccording to claim 1, the method further comprises the step of applyingreverse torsion.
 11. A method according to claim 1, wherein the step ofdeforming billet comprises rolling using a figure roller, in which aprofile of the roller comprises several sections, including a middlesection with the largest cross section; an intermediate section on bothsides of the middle section that has the smallest cross-section; and twoend sections.
 12. A method according to claim 1, the method furthercomprises the step of upsetting the billet after deforming by rollingrollers about its lateral axis, wherein the deformed billet section ismoved than the lateral deformation of the billet section.
 13. A methodaccording to claim 12, wherein the step of upsetting is done afterlongitudinal and lateral the step of rolling about the billet's axis.14. A method according to claim 12, wherein the step of upsetting issimultaneous with rolling the billet with rollers under the followingcondition: σ_(u)>σ_(i)<σ_(e), where σ_(i) is the intensity of stress onthe strained section, as calculated by taking into consideration thedeformation resistance produced by the rollers during the rollingmethod, σ_(u) is the stress caused by loss of the billet's stability,and σ_(e) is the stress caused by compression of the billet's underformed sections.
 15. A method according to claim 1, wherein the step ofdeforming is continuous and consecutively applied to the billet.
 16. Amethod according to claim 1, wherein the method deforms sections of asingle-phase alloy billet at a real strain amount of not less than 3,with a strain amount of 1.4, and the strain rate of 10¹-10⁻² s⁻¹ at atemperature of (0.3-0.5) T_(melt), where T_(melt) is melting point. 17.A method according to claim 1, wherein the method deforms sections of amulti-phase alloy billet at a real strain amount of not less than 3,with a strain amount of 1.4, and a strain rate of 10⁻¹-10⁻⁴ s⁻¹ at atemperature of (0.5-0.85) T_(melt) (where T_(melt) is melting point).18. A method according to claim 1, wherein the method deforms sectionsof a titanium-alloy billet with a lamellar microstructure at a realstrain amount not-less than 3 by the steps of applying reduction andtorsion simultaneous with rolling, the method further comprising thestep of upsetting simultaneous with the step of rolling, and then thestep of deforming at 700—Ta.t. and strain rate 10⁻¹-10⁻¹ s⁻⁴, whereTa.t. is the temperature of the allotropic transformation.
 19. A methodaccording to claim 1, wherein the method deforms sections of a titaniumalloy billet with a lamellar microstructure at a strain amount of notless than 3 by the step of reduction, and the step of applying torsionis simultaneous with the step of rolling, the method further comprisingthe step of upsetting while rolling, then the steps of applying torsionand aligning through the steps of reduction, and upsetting, anddeforming at 700—Ta.t. at a strain rate of 10⁻¹-10⁻⁴ s⁻¹.
 20. A methodaccording to claim 1, wherein the method deforms sections of a titaniumalloy billet with a lamella microstructure with not less than 1.1 timesreduction in the cross-section at Ta.t−Ta.t.+(10-50), then the sectionsare cooled at a rate of not less than 1°/s, followed steps of applyingtorsion and upsetting at a temperature not higher than 700—Ta.t. withthe strain rate of 10⁻¹-10⁻⁴ s⁻¹.
 21. A method according to claim 17,wherein the method deforms sections of heat resistant nickel billets ata temperature not higher than a temperature of complete dissolution ofthe γ′-phase.
 22. A method according to claim 1, wherein the methoddeforms the billet until a single-amount increment of strain amount iswithin 10%-20% of the specified temperature and strain amount, but doesnot lead to a change in the stress flow, σ_(f), of more than 5%-10%. 23.A method according to claim 1, wherein the method deforms the billet ata specified temperature and strain amount ξ until the step changes ofthe strain amount no longer lead to an increase of the coefficient ofthe rate sensitivity, m=(log N₁-log N₂)/(log ξ₁-log ξ₂) up to amounts of0.3-0.8; where N₁, N₂ are the amounts of pressure selected from momentpressure, compression pressure, or the extension pressure that isapplied to the billet before and after the change of the strain amountfrom the amount ξ₁ to the amount ξ₂.
 24. An article formed by the methodaccording to claim
 1. 25. A method according to claim 1, comprisingapplying the steps of reducing the billet's cross-section by applying apressure along and across the billet longitudinal axis; and deformingthe billet by applying torsion and extension forces to successivesections of the billet that are each defined by a length that is notgreater than-three times the billet diameter at the section ofapplication.
 26. A method according to claim 1, comprising repeatedlyapplying steps of reducing the billet's cross-section by applying apressure along and across the billet longitudinal axis; and deformingthe billet by applying torsion and extension forces to a section of thebillet that is defined by a length that is not greater than three timesthe billet diameter at the section of application followed by applyingsteps of reducing the billet's cross-section by applying a pressurealong and across the billet longitudinal axis; and deforming the billetby applying torsion and extension forces, to a successive section of thebillet defined by a length that is not greater than three times thebillet diameter at the section of application.
 27. A method according toclaim 1, comprising applying steps of reducing the billet'scross-section by applying a pressure along and across the billetlongitudinal axis; and deforming the billet by applying torsion andextension forces to a section of the billet that is defined by a lengththat is not greater than three times the billet diameter at the sectionof application followed by a further step of applying a deformationtechnique to the section.
 28. A method according to claim 1, comprisingapplying steps of reducing the billet's cross-section by applying apressure along and across the billet longitudinal axis; and deformingthe billet by applying torsion and extension forces at a firsttemperature to a section of the billet that is defined by a length thatis not greater than three times the billet diameter at the section ofapplication followed by applying steps of reducing the billet'scross-section by applying a pressure along and across the billetlongitudinal axis; and deforming the billet by applying torsion andextension forces at a second temperature decreased from the firsttemperature.
 29. A method according to claim 1, comprising applying thesteps of reducing the billet's cross-section to a billet of at least 150mm diameter.
 30. A method according to claim 1, comprising applying thesteps of reducing the billet's-cross-section to a billet of at least 200mm diameter.
 31. A method according to claim 1, comprising applying thesteps of reducing the billet's cross-section to a billet of at least 400mm diameter.
 32. A method according to claim 1, comprisingsimultaneously reducing the billet's cross-section by applying pressurealong and across the billet longitudinal axis and deforming the billetby applying torsion and extension forces.
 33. A method includingdeformation of at least a section of a billet through reduction of thebillet's cross-section, the method comprising: providing a billet;reducing the billet by applying pressure; rolling the billet; andapplying torsion and extension forces to deform the billet at atemperature sufficient to provide a microstructure with intrinsicphysical and mechanical characteristics.
 34. A method according to claim33, wherein the step of reducing a billet's cross-section comprisesapplying pressure.
 35. A method according to claim 33, wherein the stepof reducing a billet's cross-section comprises laterally rolling thebillet.
 36. A method according to claim 33, wherein the step of reducinga billet's cross-section comprises longitudinal and lateral rolling. 37.A method according to claim 33, wherein the step of reducing a billet'scross-section comprises rolling the billet and creating forces directedat angles to the billet.
 38. A method according to claim 33, wherein thestep of reducing a billet's cross-section comprises rolling the billetthrough a plurality of rollers.
 39. A method according to claim 33,wherein the length of the deformed billet does not exceed three minimaldiameters of the billet's reduced cross-section.
 40. A method accordingto claim 33, wherein the step of reducing of the billet comprisesapplying compression along the billet's longitudinal axis.
 41. A methodaccording to claim 33, wherein the step of deforming comprises applyingtorsion.
 42. A method according to claim 33, the method farthercomprises the step of applying reverse torsion.
 43. A method accordingto claim 33, wherein-the step of-deforming billet comprises the step ofrolling.
 44. A method according to claim 43, wherein the step of rollingcomprises rolling in rollers that comprise comprises several rollersections, including a middle section with the largest cross section; anintermediate section on both sides of the middle section that has thesmallest cross-section; and two end sections.
 45. A method according toclaim 33, the method further comprises the step of upsetting the billetafter deforming by rolling, wherein the deformed billet section is movedthan the lateral deformation of the billet section.
 46. A methodaccording to claim 45, wherein the step of upsetting is done afterlongitudinal and lateral the step of rolling.
 47. A method according toclaim 46, wherein the step of upsetting is simultaneous with rolling.48. A method according to claim 47, wherein the step of rolling isapplied under the following condition: σ_(u)>σ_(i)<σ_(e), where σ_(i) isthe intensity of stress on the strained section, as calculated by takinginto consideration the deformation resistance produced by the rollersduring the rolling method, σ_(u) is the stress caused by loss of thebillet's stability, and σ_(e) is the stress caused by compression of thebillet's under formed sections.
 49. A method according to claim 33,wherein the step of deforming is continuous and consecutively applied tothe billet.
 50. A method according to claim 33, wherein the methoddeforms sections of a single-phase alloy billet at a real strain amountof not less than 3, with a strain amount of 1.4, and the strain rate of10¹-10⁻² s⁻¹ at a temperature of (0.3-0.5) T_(melt), where T_(melt) ismelting point.
 51. A method according to claim 33, wherein the methoddeforms sections of a multi-phase alloy billet at a real strain amountof not less than 3, with a strain amount of 1.4, and a strain rate of10⁻¹-10⁻⁴ s⁻¹ at a temperature of (0.5-0.85) T_(melt) (where T_(melt) ismelting point).
 52. A method according to claim 33, wherein the methoddeforms sections of a titanium alloy billet with a lamellarmicrostructure at a real strain amount not less than 3 by the steps ofapplying reduction and torsion simultaneous with rolling, the methodfurther comprising the step of upsetting simultaneous with the step ofrolling, and then the step of deforming at 700—Ta.t. and strain rate10⁻¹-10⁻⁴ s⁻¹ where Ta.t. is the temperature of the allotropictransformation.
 53. A method according to claim 33, wherein the methoddeforms sections of a titanium alloy billet with a lamellarmicrostructure at a strain amount of not less than 3 by the step ofreduction, and the step of applying torsion is simultaneous with thestep of rolling, the method further comprising the step of upsettingwhile rolling, then the steps of applying torsion and aligning throughthe steps of reduction, and upsetting, and deforming at 700—Ta.t. at astrain rate of 10⁻¹-10⁻⁴ s⁻¹.
 54. A method according to claim 33,wherein the method deforms sections of a titanium alloy billet with alamella microstructure with not less than 1.1 times reduction in thecross-section at Ta.t−Ta.t.+(10-50), then the sections are cooled at arate of not less than 1°/s, followed steps of applying torsion andupsetting at a temperature not higher than 700—Ta.t. with the strainrate of 10⁻¹-10⁻⁴ s⁻¹.
 55. A method according to claim 54, wherein themethod deforms sections of heat resistant nickel billets at atemperature not higher than a temperature of complete dissolution of theγ′-phase.
 56. A method according to claim 33, wherein the method deformsthe billet until a single-amount increment of strain amount is within10%-20% of the specified temperature and strain amount, but does notlead to a change in the stress flow, σ_(f), of more than 5%-10%.
 57. Amethod according to claim 33, wherein the method deforms the billet at aspecified temperature and strain amount ξ until the step changes of thestrain amount no longer lead to an increase of the coefficient of therate sensitivity, m=(log N₁-log N₂)/(log ξ₁-log ξ₂) up to amounts of0.3-0.8; where N₁, N₂ are the amounts of pressure selected from momentpressure, compression pressure, or the extension pressure that isapplied to the billet before and after the change of the strain amountfrom the amount ξ₁ to the amount ξ₂.
 58. An article formed by the methodaccording to claim
 33. 59. A system for metal and alloy treatmentincluding deformation of at least a section of a billet throughreduction of the billet's cross-section, the system comprising: meansfor reducing the billet's cross-section by moving along and across abillet axis; means for rolling the billet surface; support standsmoveable in a direction along the longitudinal axis of the billet toapply an extension force to the billet; means for applying strain at apre-specified strain level by deforming the billet by applying torsionand the extension force; wherein the billet is deformed at a temperaturesufficient to provide a microstructure with intrinsic physical andmechanical characteristics.
 60. The system according to claim 59,further comprising means for upsetting the billet.